Spark-plug.



W. H. TIDMARSH.

SPARK PLUG. APPLiGATION FILED FEB.20, 1911.

1,008,21 9. Patented Nov. '7, 1911.

.57 re for PATENT OFFICE.

' TIDMARSH, OF ELGIN, ILLINOIS.

SPARK-PLUG.

Specification of Letters Patent.

Application filed February 20, 1911.

Patented Nov. 7, 1911.

Serial No. 609,753.

To all whom it may concern."

Be it known that 1, WILLIAM H. TIDMARSH, acitizen of the United States, residing at E1 in, in the county of Kane and State of Ill1nois,'have invented certain new and useful Improvements in Spark-Plugs, of which the following is a specification.-

This invention relates to spark plugs such as are commonly used in the head of a cylinder of an internal combustion engine to ignite the compressed gases therein.

The objectsof the present invention are: to provide a spark plug which will be proof against short-circuiting, and which will also be thoroughly gas-tight; to form in said plug shield members which will protect the exposed connections against fouling by dirt, oil, etc.; to provide a plug that may be easily assembled or disassembled, and one simple and inexpensive of construction; and to provide a=plug in which the tightening of the nut thereon will serve to bind every part in tight connection.

The invention further relates to the features of construction and combination of parts hereinafter described and claimed.

In the drawings, Figure 1 is an elevation of .the spark plug; Fig. 2 is a longitudinal section therethrough; Fig. 3 is a cross section, taken on line 3-3 of Fig. 2; and Fig. 4 is a plan View looking into the bottom thereof.

My inventioncomprises a conductor 5 se cured within an insulating stem 6, of porcelain or other suitable material, and held therein by means of a cap 7 in engagement with the screw-threaded surface on the outer end thereof, which conductor has revolubly mounted thereon a thumb nut 8;the nut, cap, and threaded stem constituting a binding post for the attachment of the high tension wire. The inner end of said conductor terminates in a bent portion 10, the end of which constitutes one of the sparking points for the ignition of the gases. A portion of the stem 6 near its inner end is made to taper outwardly, to provide a conical surface 11 over which a gasket 12, preferably of soft metal, fits snugly. Near the middle of the stem 6, a reduced portion 13 is formed, of smaller .diameter than the stem, with projecting lugs 14 thereon, as shown in Figs. 2 and 8, and said recessed port-ion is adapted to be surrounded by a threaded split bushing 15, having holes 16 therein in which the ,lugs 14 may rest. The stem 6 is further provided near its lower end with a plurality of dish-shaped members 17, presenting shieldlike surfaces when viewed from the bottom, as illustrated in Fig. 4. A shell 18, of porcelain or other insulating substance, is made to bear against the gasket 12.and surround the lower portion of the stem. Another gasket 19 of soft metal is positioned on the upper side of said shell between it and the body portion 20 of the plug which extends downwardly outside of said shell. Connection between the body portion 20 and the stem 6, over which the gasket 12, the shell 18, and the gasket 19, are placed, is maintained by a nut 21 formed with shoulders 22 which bear against the body portion 20, and which nut engages, along its interior threaded surface 23, the threaded split bushing 15. A short wire 24, constituting one of the ignition points, is made to extend from the lower portion of the body 20 close to the bent portion 10 of the stem 6.

It will be seen that the forces which maintain the plug-in assembled position tend also to render it thoroughly gas-tight and foul-proof. The nut 21 bearing down on the body portion 20 draws the bushing 15 tightly against the upper surface of the recessed'portion 13 of the stem 6, tending to draw said stem upward. At the same time, however, the advance of'said stem is checked by the conical surface 11 carrying the gasket 12, the shell 18, and the gasket 19, the latter of said gaskets bearing against the body portion and directly opposing further movement of the stem in the direction of the nut. It is apparent that as the nut is tightened upon the bushings a wedging action takes place. The gasket 12 is tightly compressed between the conical surface 11 and the shell 18, and being formed of'a soft metal it readilyconforms to the surfaces engaging it, to effect a tight joint therebetween. The gasket 19 also undergoes a similar compression and effectually closes any passa c that might otherwise exist between the b0 y portion 20 and the shell 18. It should also be noted that since both of the gaskets are of soft material there will be a resulting tendency to diminish the liability of cracking or breaking of the procelain stem when the nut is advanced, since the materials composing the gaskets will yieldand give as pressure is applied.

It is very essential that all connections in a spark plug should be absolutely tight and separate part to be mounted on said shell.

proof against short-oircniting. vention, the use Of the gaskets, whichfarc maintained in position by a wcdging action, has produced a plug elicctually gas-light When an internal combustion engine is oper ated for any length oil. time, it is al\\'a s the case that oil, grease, dirt, etc", comes in contact witn the end of the spark plug inserted into the cylindei: This tends in time to :t'oul the insulating parts, and causes short-circuiting, The plug of the present invention has eliminated, as far as po:-.=- sible, all exposed portions which might be fouled. As a further protection. however. to any exposed connections, l have provided the dish-shaped members mounted on the insulating stem, which i'nembers serve as shields against particles of oil, dirt, etc. it is to be understood. that my invention is not limited to the use of two shield members. as shown in the drawing, but a greater or less number may be empl -rved, as desired. It is intended that the diameter of said shield members should be nearly as great as the inside diameter of the porcelain shell. so that when the plug is assembled there Will-be practically no space left around the shield members. Should any matter be forced around the shields, hmvcver, it will be mostly lodged within the hollow portions thereof and be prevented from dropping into the cylinder, to be thrown again and again at the exposed parts oi the plug. In case the hollow portions of the shield nuanbcrs should ever collect any appreciable amount of oil and matter, the sam could be readily removed by taking the plug oil the cylinder and cleaning the parts. It is thus seen that in my invention an ell'ectual protection has been designed to prevent the fouling of the exposed parts of the spark plug, and that means have been provided to render it gas-tight.

It should be borne in run members which have been formed integral with the necessarily be so formed but In my inthat the shield described as stem need not may be made a the stem. It would also serve the purpose of the present invention fully as Well to form shield members. as part of the shell 18, or forming them separately to have the same carried by 1 claim:

1. A spark plug. comprising a body provided with a terminal at one end, the inner end of said body being hollowed to form a chamber therein, an insulating stem within said body provided with a, bore, a conductor Within said bore, having its terminal end in close proximity to the aforesaid terminal, a shield-like member formed integral with said stem near the inner end thereof, an out- *Wardly tapering portion on said stem, a trusto-conical gasket adapted to lie over vidcd with a terminal said outwardly ta poring portion, an insulating shell within the chamber formed in said body, adapted to bear against the outer surtarc o l said iruslo-co11ical gasket, a dishshaped gasket between the body and said in ulating shell, adapted to encircle Said stem at the point where its outwardly tapering portion begins, and means for advancing the stem within the body to compress both of sL-iid gasket-s, substantially as described.

.2. A spark plug, comprising a body proat one end, the inner end of said body liming hollowed to form a chamber therein, an insulating stem within said body provided with a bore, a conductor within said bore, having its terminal in close proximity to the aforesaid terminal, a shieldlike member Formed integral with said stein near the inner end lhereof,,a reduced porlion in said stem, an outwardly tapering portion on said stem, a trusto-conical gasket :ulaplcd to lie portion, an insulating shell within the chantbnr l'ormcd in said body, adapted to bear against the outer surface of said frusto- ('(Jllll'lll gasket, a dish-shaped gasket between the body and said insulating shell, adapted lo encircle said stem at the point where its outwardly tapering portion begins, and imzans 'l'or mlva-ncing the stem within the body to connn'css both of said gaskets, said means comprising a locking member adapted to bear against the outer end of said body, and a sleeve member adapted to embrace the reduced portion o'l" said stem, the said locking mcmbc" also being in engagement with said sleeve member and adapted to move the same, whereby the stem is advanced within the body to compress both of said gaskets, substantially as described.

3. An insulating stem for a spark plug, having a concave shield-like member of insulatingmaterial adjacent the inner end lhercot, the concave surface of said member facing the body of the plug, substantially as described.

4. A spark plug comprising a hollow body provided with a terminal at one end, an insulating stem within the body provided with a bore, a conductor within said bore having its terminal end in close proximity to the aforesaid terminal, and a concave shield-like member of insulating material :uljacent the inner end of said plug, the concave surface of said mcn'lbcr facing the body of: the plug, substantially as described.

5. A. spark plug comprising a hollow body provided with a terminal at one end, an insulating stem within the body provided with a bore, a conductor within said bore having its terminal end in close proximity to the aforesaid terminal, and a concave shield-like member of insulating material carried by said stem adjacent the inner end of said plug, the concave surface of said over said outwardly tapering of the vin sub: b7 l face of said member facing the body of the plug, suljisi'antiall as described.

T. A spark plug con'iprising a hollow body portion provided with a terminal at one end, an insulating Stem within the body provided with a bore, av conductor \Viilliil said horn having terminal end in close proximity to the aforesaid terminal, a concave shioldlike member of insulating mai'rrial adjacvnl' the inner and of said plug, the ooncnve surfaco of said member facing tho body of the plug, a gasket between said slum and the body poriioin and 11121118 'ior oompro ing said gasket i'liorohntwenn to form a gas-tight connection, suhldnntially an described.

8. A, spark plug comprising a. hollow bod}, provided with a terminal atv one mid. an ininilaiing sinm within U10 body provided with a horn a condm'lor within said bore harm; its terminal end in close proximity to the aforesaid tormini, a concave shiold-- iilao member of insulating; material carried by said stein adjacent the inner end of said plug, the concave surface of said nionaoor failing the body of the plug, a gasket lWQGI'i @aid stem and the body portion, and means for compressing said gasket thcroho tween to form gasiigiht connection, substantially as described. 7

i). In a spark plug, the oonihinaiion with. a body portion, an insulaiing stein providnd with a reduced portion intermediate its em .a and packing adapi'e-d to'i orm a fight connection between said body and. Siam, oi moans for placing said packing undrr coinpression, said moans consisting of a .l'iiwd memhier secured to tho rho in *nd portion thereof, and. hold a il; dinal movement thoroaiong, and a roiziiiahio memhor in ongngumrni, iliQE'OWiill, the said rotatable. n'imniwr hoing' ada 'nod to hum against the body of the. plug. and when rotated upon the said fixed member to ads anon the body Or the plug with respect to tho sl'mn, whorohy the packing llrvroholtwcon iii comprcazrsod. substantially as doscri od.

/ M. H. TIDMARSEL ii itnosses:

' EPIIRAIM BANKING, ALK 2R BANMN G. 

